1. Field of the Invention
The present invention relates to a pattern forming method for forming patterns in devices, such as semiconductor devices and liquid crystal devices, a photomask manufacturing method, a semiconductor device manufacturing method, and a computer program product.
2. Description of the Related Art
Wet process is widely used as a substrate processing technique in the manufacturing process for semiconductor devices and liquid crystal displays. Especially, a splay method is positively studied as a development treatment after a photosensitive resin is exposed.
In a conventional splay method, chemical is supplied onto a substrate to be processed with the substrate is being rotated. The chemical is supplied by a chemical supply section disposed above the substrate.
However, with the chemical supply section, it is very difficult to uniform a discharge pressure of the chemical or a supply amount of the chemical per unit area both on central portion and peripheral portion. Therefore, it is very difficult to obtain uniform in-plane development accuracy on the substrate. Such the process accuracy problem similarly occurs in substrate processing other than the development processing.
In addition, as the development proceeds, dissolution products, low density developing solution, and the like occur as by-products. Generally, the dissolution products and low density developing solution, and the like are considered to have the effect of inhibiting dissolution of a photosensitive thin film. Since the dissolution products occur corresponding to the pattern density on the substrate, consequently, the dissolution products is made to have some distribution on the substrate. Thereafter, the dissolution products receive forces such as centrifugal forces generated by the rotation of the substrate, therefore the dissolution products do not move uniformly on the substrate. Even by such the reason, the in-plane uniform process accuracy cannot be obtained by the conventional spray method.
A substrate processing method using a suction nozzle to generate a chemical flow during the development is proposed. For example, there is proposed a nozzle having a chemical discharge opening and a chemical suction opening, and a substrate processing method using the nozzle (see Jpn. Pat. Appln. KOKAI Publication No. 2002-252167, for example).
When a developing solution is used as the chemical, i.e., the developing solution is discharged from the developing solution discharge opening while the developing solution is sucked from a developing solution suction opening, the substrate processing method is relating to a method that the substrate is processed by scanning the substrate with the nozzle which is positioned near the substrate. And the substrate processing method is such a method to realize chemical replacement between the patterns, furthermore to reduce pattern dimension difference resulting from the pattern density by positioning the nozzle near the substrate and accelerating the chemical flow on the substrate.
However, even in such the substrate processing method, it is still difficult to suppress development inhibition (development loading effect) caused by dissolution products (development by-products) and to sufficiently suppress CD variation.
In the case of the development process including the substrate rotation, flow rate and flow direction of the dissolution products are not uniform within the plane. This makes it very difficult to correct the dimension variation due to the dissolution products at exposure process by using the same function on the whole plane, therefore causing a problem that the CDs vary over the plane.
In addition, according to post-exposure baking (PEB), for example, if a chemically amplified resist is used as the photosensitive resin, acid generated by exposure process during PEB evaporates depending on the intensity and direction of an atmospheric flow (gas flow) in a baker. The evaporated acid deposits on the resist again or enter into the resist again. Such the re-deposition or re-entrance of the acid results in sensitivity variation and the resist is influenced to the extent that the pattern dimension changes.